Typically, the installation of a wireless sensor network (WSN) requires the placement of network nodes, for example sensors and/or routers, in optimal locations in an environment, such as a building or a home. Usually this task is carried out by expert installation personnel. The task of determining a suitable position for a WSN node is performed by skilled personnel using special installation equipment.
Sensor nodes may be connected in networks having different network topologies, for example a star topology, a tree topology or a mesh topology. The route via which a message may travel depends strongly on what type of topology is used. For example, in a network based on a star topology, network nodes will always communicate through a central node. In contrast, in a network based on a tree topology or a mesh topology, the messages may take different routes to a destination without necessarily passing through a central node.
In topologies in which messages can take different routes, a network may change its routing such that some routes become heavily used. In such networks, the location of a node in a network has an effect on the behavior of the network. For example, the routing algorithms of the network may choose a path with higher latency based on the relative location of the nodes in the network, which in turn may affect the network application.
Such changes in the message routes may arise due to changes in the building situation over time. For example, some walls may have been added or removed in order to create different rooms. Furthermore, shifting around furniture may affect the signal propagation in the environment, Which may lead to a changed route. In addition to changes in the building structure, the presence of people and electromagnetic interferers may also affect the network.
Installing a WSN in a commercial building or a home may involve measuring the signal strength in the environment and, based on these measurements, placing the WSN nodes in optimal locations. These locations could be optimal with respect to network coverage, message latency and/or node power usage.
When home owners want to install a WSN, they generally do not have access to special installation tools. Furthermore, the methods described in installation instructions for a WSN are usually not intuitive and difficult to follow for unskilled individuals. In home environments, this way of working would require that experts be hired, which would lead to higher costs for a WSN installation.
Even when the networks are designed and installed by experts on the basis of conventional signal strength measurements, dynamic effects—such as changes to a building, movement of furniture, intermittent RF disturbances (e.g. Wi-Fi) and people moving around—will not generally be taken into account. Thus, signal strength measurements as used in conventional WSN installation procedures only provide a static view of the RE conditions in a building or a home. In other words, the view is inherently limited to the RE conditions measured at the time of installation of the WSN. If in the case of a change in the environment the WSN does not work properly, then the experts have to be hired again to perform new signal strength measurements, which is costly and still does not represent a dynamic solution.